Moreover, macrophages have a significant role in the link between the innate and adaptive immune system [8] and are another source of inflammatory cytokines associated with insulin resistance.[12] Additionally, obesity induces a phenotypic switch in macrophage polarization and increases proinflammatory cytokines (TNF-α, IL1β, MCP-1). The gene discussed is CCL2; the disease is obesity due to melanocortin 4 receptor deficiency.